July 2011 Tech Talk
By Matt Driskell
When Luke approached me about doing an article for the tech section of TBIR he said I could write on any subject I chose. It didn’t take long for me to decide. Since I have been racing for over 25 years and have always done my own engines and now own and operate Driskell Racing Engines my obvious choice was to talk about engines. When I started as a 14 year old kid I knew nothing about engines and have learned by digging in and figuring out what works and what doesn’t. I have had a lot of good advice and some not so good and have used that along with my knowledge and experience to get where I am today. At Driskell Racing Engines we build a variety of engines from small blocks for street machines to 700+ inch engines for drag and truck pulls plus some circle track engines. We work on all brands of engines so that keeps us on our toes.
Matt's current personal ride: a 2010 Mullis 4-link Dragster
I am going to share with you some of the issues that I see customers facing and some of our recommendations that will help your engine last longer, and help you understand why certain things are important and make your investment in your engine last.
To start with I believe it is key to find a trustworthy engine builder or machine shop to work with. Having someone to call to help through problems is something that everyone needs no matter how big or how small or what type of business you are in. Communication is vital especially when there has been an issue with your engine. If you bring it in and we take a look and sure enough it has kicked the rods out we might be able to figure out what happened but as the owner hopefully you can provide us with some info to help keep this from happening again. At Driskell Racing Engine we take the time to talk with the customer to provide them with an engine that will perform, last, and try to fall within their budget.
Maintenance is crucial to making your engine last so let’s take a look at what you need to be doing and or looking at.
OIL: Racing engine oils have gotten a lot of attention in the past few years with the government regulations taking out most of the anti wear additives. Some oils will say they are racing oil but they still have the American Petroleum Institute (API) starburst on it. If it has the API starburst it can only contain a small amount of antiwear additives. Those additives damage O2 sensors, catalytic converters and are not needed in the normal street driven car. In a race engine it is a different story as our enemy is friction and we need the additives that a true race oil has. I personally use Lucas oil in my race cars and they have great products and do so much for our sport but there are many companies making good race oils. Viscosity is the next thing to talk about; generally I recommend 20/50. There are several factors that determine what weight to run; clearances, fuel, horsepower, stroke, and oil temp. Oil temp is one of the big factors to determine viscosity and I am not sure when the last time I have seen an oil temp gauge in a sportsman car. A pro stock car or comp car can run the ultra thin oils because they have the ability to control their oil temp. As a sportsman racer we might run several hours apart or make runs minutes apart and that is why I like to stay with 20/50 due to the wide variety of conditions the engine will see. On a new or fresh engine we will put in a break in oil, this helps the rings to seat faster and has the additives that are needed and not some of the friction modifiers that the race oil has. With this type of oil we usually see the rings seat in 3 to 5 pulls. We then advise the customer they can run it for the first time out and then change it. The break in oil is conventional oil and it is not advised to put in a synthetic on a new engine as it can cause ring seating issues. I personally like to use either a conventional oil or semi synthetic in most applications. As far as oil change intervals I change conventional oil about every 20 runs and the semi or full synthetic in the 40-50 run range. You cannot change it too often but unless you suspect something is going wrong you are probably wasting money. There are exceptions to every rule such as if you are running in a very harsh or dirty environment, get fuel contamination or other factors that may cause the oil to break down faster.
OIL FILTER: A high quality racing oil filter such as K&N is a must. I have seen so many of the cheap filters collapse inside and that can cause the engine to starve for oil and then the destruction sets in. The cleanable/reusable filters work just fine as long as you use one that has the proper micron size for your application. One thing to remember about those is that the element does not last forever. They can get plugged with lint and other small particles that you cannot get out so eventually they will need to be replaced. I had a customer come to dyno and no matter what we did the oil pressure on the engine was low. We looked everything over and couldn’t come up with anything, I asked about their system 1 filter and they said they had owned it since they started racing more that 10 years ago. We took the element out and replaced it with a new one and the oil pressure issue was gone. Regardless of the type of filter we recommend that it is cut apart or inspected every time the oil is changed. Many problems can be caught if you see something abnormal in the filter
OIL LEVEL: How much oil to run is a question that comes up often. Most oil pans have a recommended amount of oil and that is a good place to start. We learn a lot about how much oil to put in on the dyno but one factor we don’t have working for us is acceleration pushing the oil to the back of the pan. Too much oil can cause problems just like too little will. With the use of longer stroke cranks and wet sump oil systems the problem gets worse. We freshened a customer’s 598 bracket engine, it was nothing fancy and the oil pan was a basic plan that would clear the 4 ½ stroke. As we started to dyno the oil pressure was not acting right. It would jump around as the RPM came up and then eventually would start to drop off steadily. It was not making great power either so we started taking out ½ quart at a time. We took out 1 ½ quarts of oil and picked up almost 50 horsepower all from getting the crank and rods to quit running through the oil and the oil pressure was steady throughout the pull. You need to pass along any oil pressure issues to your engine builder or machine shop so the problem can be resolved before any major damage occurs. A data logger can give you a look at what is happening to your oil pressure during a run. You cannot watch the gauge close enough to see everything that happens during a run. It can be quite eye opening to be able to graph the oil pressure for the entire run. I know that most run a wet sump oil system and they do work quite well but all have the inherent problem that all the oil is in the pan and climbs up the back of the pan and into the crank and rods when the car is launched. Many of the new oil pans and pump/pickup combos help this but it can not be stopped just like the oil pressure dropping and the end of the run when on the brakes. A dry sump oil system is the ultimate oil system, period. The oil is kept in the remote tank so it cools much better and you always have a supply of non aerated oil to supply the pump and engine. There are no more oil pressure issues in the shut down. Depending on the stroke of the engine and design of the old oil pan it can be worth from a few horsepower to 30 or more on the dyno. I have found that regardless of what the dyno shows it is worth ET on the race track by getting all that oil out of the pan. It is quite an investment but one that I feel is worth looking at and discussing with your engine builder.
VALVE LASH: This is an area that I try to stress to every customer. Two of the more common things that tend to go wrong are a broken roller lifter or valve spring. With the advancements in cylinder heads and increased horsepower levels these two items get stressed to the limit. With Top Sportsman/Dragster and fast bracket engine becoming more popular the stress on the parts just keeps getting worse. No one would have believed 15 years ago that you could run a sportsman engine with valve lift of 1 inch and drive the thing around like it was a passenger car but that is what we do. Springs and lifters have become so much more reliable but when one breaks it can cause a lot of damage. A broken lifter throws all of the debris right down on the crank and rods and it slings it right up the cylinder walls. The piston skirts are now trashed along with the cylinder wall. When a valve spring breaks it will continue to run till either the valve tags the piston long enough and breaks the head off or it spits the keepers out of the retainer and then the whole valve trying to get cozy with the piston and combustion chamber. There’s not room for everything and it becomes a real mess in a hurry. Most valve covers have 8 or less fasteners and they are easily accessible so if you are not taking them off to check them your are being lazy. If you run the valves after every race you may be able to catch a lifter before it completely fails. If your valve lash doesn’t move from week to week and all of the sudden you have one .005 loose you better check it out. You can also visually inspect the valve springs for any broken coils and use one of the on head spring checkers to see if the pressure is where it is supposed to be. Most of the time a spring will just break an outer or inner so it is pretty easy to catch it before all hell breaks loose. I like to run the valves cold that way the temperature of the engine doesn’t become a factor. With aluminum blocks and spread port heads the lash will move as much as .010 to .018 depending on how hot the engine is. So check the lash and springs often. The roller lifters need oil to survive and that is really important on cold start up. When the engine is started it needs to get to a high idle to get oil flowing to the lifters. Starting it and letting it chug along at 700 rpm is not a good idea for a race engine. Try to get the idle to 1500 to 1800 to get the oil flowing and your lifters will appreciate it. As James Monroe said in his article having a plan of action for changing a lifter or spring at the track is something you need to plan for. Running around trying to figure out how to change one or where to get parts could cost you time that you might not have so be prepared for the worst.
This kid running the valves on his Camaro is your author, Matt Driskell... Circa 1985 at the Tulsa, OK national event.
Ignition & Timing: One of the most common mistakes we see is people not checking their ignition timing once it leaves our shop. Most believe that since we have ran it on the dyno the timing is set and while that is true there are differences in ignition boxes. We use a MSD 7AL-3 on the dyno and will start by setting the timing as high as I think we will run it and then retard it by putting a chip in one of the retards on the box. This works great because we don’t have to recheck the timing every time we want to change it. So if we have a 3 degree chip in the box on the dyno and even if you have the same box but all zeros it is going to be too far advanced and if you have a different box then it could be off even more. Once we have ran the engine on the dyno we give recommendations for different atmospheric conditions of what timing to run. It is always safer to be a little on the low side of timing as too much timing can cause detonation which can lead to disastrous problems. In general, when it is cool and dry you need less timing and when hot and muggy you need more timing. When we go from spring to summer you probably don’t need to move it more than a couple of degrees. It seems that everyone can remember to advance the timing on the first hot day when the car is slow but no one seems to remember in the fall on the first cold day to retard it, be sure to keep an eye on conditions and move it accordingly to keep your engine running to its peak potential. Check your distributor by taking the cap off regularly and inspecting it for and wear of corrosion. While it’s off, grab the rotor and make sure it is tight and doesn’t move more than it should. In a crank trigger or locked out distributor a lot of movement could mean the gear is worn and needs replacing. In the crank trigger distributor the small bolt the holds the rotor base will sometimes work its way loose and can then cause the rotor to make contact with the cap. It is also a good idea to check the plug wires for any cracks or burned. Use an ohm meter to check the resistance to be sure they are in good shape. The spark plugs are not like your passenger car and will run forever, take them out and inspect all of them. They can show problems such as if one looks way different from the rest. When the center electrode starts to show wear, like the edges of it getting rounded off it is time to replace or if the porcelain is all glazed over replace them. When they start to get worn the gap increases and that puts more strain on the wires and cap so replace them regularly. When looking at the plugs and trying to read them for jetting purposes remember you need to install new plugs and then shut it off at the finish line to be able to get an accurate reading.
Carb and Fuel: Most of the time the carb gets overlooked, it’s still running good so don’t mess with it. Well it does require a little maintenance. To start with the air bleeds in the top of the carb need cleaned regularly. A small change in air bleed can make a big change in the overall jetting; a few thousandths can make a big difference, so it doesn’t take much dirt to cause a problem. Use carb cleaner and then blow them out to keep things happy. A little lube on all the moving parts will also help to keep it working in tip top condition. When checking floats remember to have the car running with the proper fuel pressure. The fuel pressure will cause the float level to change a lot, this is especially true with a belt drive fuel system. At idle with low pressure the floats will be low so rev it up so you have a least 6-7 pounds of fuel pressure when checking. The fuel pressure can be a source of headaches if you have no way to monitor it down track. You can set it in the pits but there can be other issues that can cause it to be high or low going down track. If you are having issues that you think might be related to fuel pressure find a way to monitor it going down the track and you might be amazed at what you see. With some systems the fuel pressure will change very little from idle to all the way down the track and others can change a lot. Checking this can help you to determine what you might need to do to fix the problem. When using any type of power adder this is even more important. With nitrous the fuel pressure is very important to the tune up. I recommend that the whole fuel system be checked out and or rebuilt every season to ward off and problems. The floats in the carb can get heavy from fuel, they can get bent from a backfire, the metering blocks can get plugged in areas that you can’t clean so sending it in to have a quality company like APD or any of the great carb builders go through it to freshen it. The fuel pump might be working fine but the diaphragm in the pump does have a tendency to start leaking at the absolutely worst time so spending a little to have it freshened up can save you in the long run. While on the subject of fuel systems we might as well touch on the fuel itself. Be sure to use a fuel that is compatible with you combination. The compression, rpm, power adders all make a difference in what octane and burn rate of fuel you need. I use and sell VP products and they make a fuel that will cover any application you have so be sure to call to make sure the fuel you are using or thinking of buying is correct for you application. I often hear people say they are buying a fuel because it is cheaper. My reply is always the same, how much do you have in your whole racing operation? Let’s assume we are talking gasoline because 99.9% pure methanol is 99.9% no matter who you buy from or at least is supposed to be. If you used 3- 55 gallon drums of gasoline a year and what you really needed to use was 200 per drum higher that’s $600 and how much of your total racing operation that is and how much will it cost if you use the cheaper stuff and it causes a problem in the long run.
Matt Driskell's home away from home: the engine room at Driskell Racing Engines
Other: People often ask how long a part will last and the answer to that is, right up till the time it breaks. I do believe that you need to cycle all the parts out at certain intervals. How you are using the engine has a lot to do with that. Does it make 500hp or 1500hp and how many RPMs does it turn are a couple of the factors to look at. RPM stands for Replace Parts More. In some classes and forms of motor sports RPM is king but for bracket racing it is not as important. That is one thing to keep in mind when building an engine. If you build something that wants to run from 6500 to 8500 rpm and then only turn it 7000 it probably won’t run very well or be very consistent, or if you build something to run to 7000 and then turn it 8500 it might have an oil pan failure. You know oil pan failed to contain all the parts. So buy or build an engine that works for your racing and your budget. It may sound cool to build an engine that runs 4.30’s to bracket race but the maintenance that comes with it may not be worth it. It is harder and valve springs, lifters, and pistons just to name a few. That’s not to mention it has to have fresh tires more often, is harder on the trans and rear end, brakes wear out faster and the list goes on. It can be done but just be prepared for the extra expense and wear that goes with it. Most of the time during a freshen up we will replace valve springs, lifters, rings, bearings, gaskets, check all clearances and do all necessary machine work. We replace rod bolts either every freshen or every other depending on the engine. I will always advise the customer to replace the rod bolts as a broken rod bolt will cause damage in the thousands of dollars compared to the $150 or so that it takes to replace them. In the higher horsepower engines pistons have to be replaced more often so be sure to look for cracks of other damage to them. The valves in a race engine take a beating so cycling them out every 2-3 years depending on usage is advised. All the other parts need to be magnufluxed and or checked by a professional to make sure it is able to be used again. These are just a few of the items we look and replace. I would advise you to contact your engine builder or parts manufacture on the life expectancy on all of the parts in the engine and when it may be time to replace.
Risk Assessment: When is a risk worth it? If you are going up for 2nd round and you find you have a lifter broke I would say park it then because even if you win the round the damage done is probably not worth it and more than likely you couldn’t get it fixed or be able to run the other 5-8 rounds it would take to win. On the other hand if you are in the finals of a big race or involved in a tight points race then maybe the risk is worth it. Just remember sometimes it is better to lose the battle and win the war. With the popularity of top sportsman/dragster it is common to see a racer take their regular fast bracket car to race these events but at these events they might not be fast enough. So when faced with this is it worth trying to make a last minute effort to throw nitrous on it or try something else just to try and make the show. Well you could make a huge mess out of your engine and still not qualify or be able to run it like that for the whole race so at that point the risk is not worth it. Now a carefully planned out nitrous system in place before the event can work quite well and the results be worth it. When picking out an engine or engine parts there are always going to be choices. I say go with the best you can afford to do and sometimes waiting to be able to get the good parts is the best choice. To go buy a killer set of heads and then use a cheap crank or rods is not worth it. Have a well thought out plan or let a professional help you and you will have an engine that has the correct parts and should give you good service. To tie in with the previous paragraph have a set plan of when to cycle out parts in the engine so you can avoid catastrophic failure if possible.
Dynoing: I have had customers that had never dynoed anything before and were actually against the idea of it. I usually ask them if they ever take their car or truck to be worked and when they say they have I ask if the mechanic took it for a test drive. Every mechanic I know of checks out their work with a test drive so the engine builder should be no different. Not only can we verify that it makes the power it should but that it has no leaks or other issues when you put it in the car. Now if the car doesn’t perform like it should the list of things to look at just got a lot shorter as the engine ran fine on the dyno. With the high cost of fuel and entry fees it doesn’t take long to make the dyno session justify itself. You will now know what the jetting and timing should be and what RPM range it wants to run in. A lot of the time we actually find problems with the customers parts that aren’t worked on during the actual freshen up such as carbs, ignition parts, water pumps, and general drivability problems. An engine that is tuned properly will run more consistent and live longer. One thing to remember about dynos is that they are just a tool, it is just going to tell you what kind of power your engine makes and can help you optimize it. It gets very tricky trying to compare numbers from one dyno to another. Different dyno’s read different and the dyno can be manipulated to show whatever the operator wants it to read. Big numbers don’t really mean anything except bragging rights, the racetrack is the true test and the scoreboards won’t lie so keep that in mind.
Data loggers: I just want to touch on this for a minute, the basic information that a data logger provides can not only help you determine any problems but can help you to make your car more consistent. Being able to track oil pressure, fuel pressure, volts, rpm, and driveshaft rpm is something that most all basic systems can track. It can be eye opening to be able to see what the oil, or fuel pressure does going down track. When faced with an issue it can help determine where to look and can maybe even keep major disaster from happening. I personally had an engine that the bearings would not look very good at the end of the season. The first data logger I had immediately showed the oil pressure moving around during the run. I determined that I had about ½ qt too little oil in the dry sump tank and toward the end of the run it would cause it to start to drop. After that the bearings looked great, now that was a simple problem but it was not able to be noticed by trying to look at the gauge going down the track at 180 mph. When I have a customer come to me at the races and ask what they think a problem might be it is very tough to diagnose with no or little info to go on. Eventually most can be solved but it could take several runs or weeks of problems to find when the problem could be right there in front of you courtesy of the data logger. Being able to follow what the driveshaft speed does can help spot tire spin on the starting line or down track bumps that may cause tire spin. Sometimes you can move shift points or starting line rpm to help control that or you can know for certain why your car is slower in one lane versus the other.
The Driskell Racing Engines shop, located in Wellsville, KS.
In closing I would like to remind you that it is your engine and your responsibility to take care of it. A little preventative maintenance will go along way to making your investment last. I hope this information can help your racing operation or at least be thought provoking.